The invention relates to a device for preventing contact between the upper and lower premolars and molars of a patient in order to prevent the transfer of neural information, generated by tooth contact in the vicinity of the masticatory apparatus and at the same time to fix the mandible in a centric relation position of the temporomandibular joints at the smallest possible opening angle. The term "centric relation position" is understood to mean the most posterior position of the jaw hinges from which the mandible describes a purely rotational motion. On an articulator, this is the initial position for any peripheral movement. This joint position is an eminently important measurement variable in prosthetics, because it is reproducible and is the initial point of any mandibular motion. In transferring the maxillary and mandibular dental casts into an articulator, a row of teeth, for example the row of the maxilla, must be associated with respect to the patient to the axis of rotation of the articulator, and in a second phase the mandible must be associated with the already articulated-in maxilla in precisely this centric relation position. This provides largely coherent geometrical preconditions for motion simulation between the motion simulator and the patient.
The purpose of interrupting the neural impulses (deprogramming) is to recognize problematic influences (premature contacts, dysfunctions) in the diagnostic phase and to suppress them in the phase of odontoscopy in centric relation, during which the mandible cast is attached to the articulator.
By introducing a suitable device between the front teeth of the upper jaw, or maxilla, and lower jaw, or mandible, the tooth contacts can be infinitely graduatedly overcome, and with a suitable head posture, both jaw joints are compulsorily brought into a centric position (extreme dorsal/cranial posterior position) and kept in this position by supporting the front teeth on the device.
Leaf gauges have for instance been used until now as a suitable device for this purpose; for hygienic reasons and because of the danger of injury, instead of metal foils, thin plastic sheets have been combined in bundles in these gauges, but unlike the feeler gauges known in tool construction, the sheets are of uniform thicknesses. These leaf gauges are somewhat inconvenient to use; the required thickness for spacing apart of the front teeth must be continually corrected and adjusted by inserting small leaves or plates and removing them again, or adding or subtracting them. The magnitude of the distance, once found, is recorded by counting off the required number of leaves. This leaf gauge is difficult to sterilize.
In the article by Woelfel, entitled "Craniomandibular Function and Dysfunction", The Journal of Prosthetic Dentistry, Vol. 56, No. 6, December 1986, pp. 716 ff., a status description of some methods and apparatus for recording the jaw relation in the centric relation position is given. There is described a new centric relation system which includes a leaf gauge composed of a number of paper strips joined together along a short side, giving the gauge the shape of a long, narrow book or notepad. The individual "pages" of this book are of different colors and thus marked as blocks of variable thickness, so that certain standard thicknesses can be joined together. Since the front teeth on the one hand must now be spaced apart at least far enough to take the premolars and molars out of contact with one another, yet on the other hand the smallest possible opening angle must be sought (to prevent forward motion of the jaw joints), individual sheets must be removed or added, until both goals (teeth out of contact at minimum possible opening) are attained.
The removal and addition of individual sheets make this paper notepad relatively inconvenient to manipulate, and the accuracy which they achieve is questionable because of the resiliency, or compressibility of the paper or sliding of the layers of paper over one another. Ascertaining the actual thickness is more difficult, so repeatability for later procedures is not assured. Since the sheets can be used only once, it is also relatively expensive to use. This gauge is also described in U.S. Pat. No. 4,654,005.